Positive electrode structure of cylindrical battery

Abstract

The utility model relates to an anode structure of a cylindrical battery, which belongs to the technical field of batteries and comprises an aluminum shell and a roll core sleeved inside the aluminum shell, an anode end of the aluminum shell is provided with an anode top cover, an explosion-proof valve used for exhausting gas is mounted inside the anode top cover, an anode collector plate is arranged at the inner end of the anode top cover, and the anode collector plate is connected with the aluminum shell. At least three layers of annular step surfaces are sequentially arranged on the inner side of the positive electrode end of the aluminum shell from outside to inside, the inner diameter of the step surface on the outermost side is smaller than the diameter of a roll core, the step surface on the innermost side is fixedly installed on the positive electrode current collecting disc, and the step surface on the last but one stage is installed on the positive electrode top cover in an attached mode; the positive collector plate comprises a fixing piece, a through hole is formed in the center of the fixing piece, and at least three protruding parts are evenly arranged at the top end of the fixing piece around the through hole. According to the utility model, the safety problem caused by the fact that the explosion-proof valve at the positive electrode end of the cylindrical battery is blocked and cannot be opened in time can be effectively avoided, and the safety of the battery cell is effectively ensured.

Description

Technical Field

[0001] The utility model relates to a positive electrode structure of a cylindrical battery, belonging to the technical field of batteries. Background Art

[0002] Currently, facing numerous challenges such as resource shortages and environmental pollution, sustainable development has become a global consensus. Under the "dual carbon" strategic goal, new energy sources will gradually replace traditional, environmentally polluting energy sources. Batteries, as a carrier for storing electrical energy, can be used to store and transport electricity generated by power plants, and are of great significance to the development of the new energy industry.

[0003] Lithium-ion batteries, with their high capacity density, high specific energy, and long cycle life, have become the battery of choice for portable electronics, electric vehicles, and energy storage, and are finding increasingly widespread use. In addition to their high capacity, batteries must also offer excellent safety and a long cycle life to meet usage standards and satisfy consumer needs.

[0004] As one of the technological advancements, large cylindrical batteries are expected to promote the iterative upgrade of power battery technology. Specifically, compared to prismatic and pouch-type lithium-ion batteries, cylindrical lithium-ion batteries offer advantages such as high production yield, good consistency, and a high degree of production automation. These advantages are significant in the electric vehicle sector and are expected to become the optimal solution for mid- to high-end electric vehicles.

[0005] When the height of existing large cylindrical batteries exceeds a certain value, explosion-proof valves will be opened at both ends to ensure the safety of the battery cells.

[0006] In the existing technical solution, the positive electrode current collector and the positive electrode top cover are directly welded, and an explosion-proof valve is provided at the positive end of the large cylindrical battery cell. Under test conditions such as overcharging and thermal runaway, the coil core and the positive electrode current collector can easily block the explosion-proof valve, causing the explosion-proof valve to fail to open in time, and the positive electrode top cover and the coil core to be ejected entirely, creating a safety risk.

[0007] A battery disclosed in Chinese utility model patent publication number CN215451578U includes a battery cell body and a cap assembly connected to the end of the battery cell body, the cap assembly including a cap member, the cap member is provided with an explosion-proof valve and a liquid injection hole; the explosion-proof valve or the liquid injection hole is located at the center of the cap member, and a sealing component is provided at the liquid injection hole; or, the cap member is provided with an explosion-proof valve, the explosion-proof valve is provided with a liquid injection hole, and a sealing component for sealing the liquid injection hole is provided at the liquid injection hole.

[0008] The above reference example is provided with both an explosion-proof valve and a liquid injection hole. The explosion-proof valve can be used to relieve pressure inside the battery to meet the needs of cylindrical batteries of various capacities, especially large-capacity cylindrical batteries; the liquid injection hole is used for injection or exhaust, and the battery can achieve closed-mouth injection. However, in the event of overcharging, thermal runaway, etc., the winding core and the positive electrode current collecting plate can easily block the explosion-proof valve, resulting in the explosion-proof valve being unable to open in time, posing a safety risk, and therefore urgently needs improvement. Utility Model Content

[0009] In order to overcome the shortcomings of the above-mentioned prior art, the utility model designs a positive electrode structure of a cylindrical battery, which can effectively avoid the safety problems caused by the blockage of the explosion-proof valve at the positive end of the cylindrical battery and the inability to open the valve in time, thereby effectively ensuring the safety of the battery cell.

[0010] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0011] A positive electrode structure of a cylindrical battery, comprising an aluminum shell and a winding core sleeved inside the aluminum shell, wherein the positive end of the aluminum shell is provided with a positive electrode top cover, an explosion-proof valve for exhausting gas is installed inside the positive electrode top cover, and a positive electrode collecting disk is provided at the inner end of the positive electrode top cover, and at least three layers of step surfaces, all of which are annular, are provided on the inner side of the positive end of the aluminum shell from the outside to the inside, the inner diameter of the outermost step surface is smaller than the diameter of the winding core, the innermost step surface is fixedly installed with the positive electrode collecting disk, and the step surface of the second-to-last level is fitted with the positive electrode top cover; the positive electrode collecting disk includes a fixing plate, a through hole is provided at the center of the fixing plate, and at least three protrusions are evenly provided around the through hole at the top of the fixing plate.

[0012] Furthermore, the step surface is provided with four layers, namely the first step end surface, the second step end surface, the third step end surface and the fourth step end surface. The width of the first step end surface is at least 1 mm, the width of the second step end surface is at least 0.5 mm, and the thickness of the fourth step end surface is at least 0.3 mm.

[0013] Furthermore, a vertical distance between an end surface of the second step and an end surface of the first step is at least 0.1 mm.

[0014] Furthermore, there are five protrusions, and one end of each protrusion is connected to the through hole, and the other end is arranged near the edge of the fixing plate.

[0015] Furthermore, the distance between the free end of the protrusion and the edge of the fixing plate is at least 1 mm.

[0016] Furthermore, the height of the protrusion is at least 0.1 mm.

[0017] Furthermore, the positive electrode top cover includes a top cover plate, a mounting hole matching the explosion-proof valve is provided at the center of the top cover plate, and an explosion-proof patch is fitted on the top of the mounting hole.

[0018] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0019] 1. The present invention ensures that there is a sufficient pressure relief channel between the explosion-proof valve and the winding core by setting the fourth-step step end surface of the aluminum shell and the raised portion of the positive current collecting disk. The inner diameter of the first-step step end surface of the aluminum shell is smaller than the diameter of the winding core, which can ensure that the winding core will not be ejected, thereby solving the problem of safety risks caused by the explosion-proof valve at the positive end of the cylindrical battery being blocked and unable to open the valve in time.

[0020] 2. The utility model sets the mounting hole at the center of the top cover plate, that is, the explosion-proof valve is set at the center of the top cover plate. The gas generated instantaneously during safety tests such as overcharging and thermal runaway can be gathered at the center and discharged smoothly, thereby ensuring the safety of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the installation structure of the utility model;

[0022] Figure 2 It is a schematic diagram of the cross-sectional structure of the utility model;

[0023] Figure 3 It is an exploded view of the utility model;

[0024] Figure 4 It is a schematic diagram of the cross-sectional structure of the aluminum shell of the utility model.

[0025] The figures are marked as follows: 1. Aluminum shell; 11. First-level step end face; 12. Second-level step end face; 13. Third-level step end face; 14. Fourth-level step end face; 2. Positive electrode top cover; 21. Top cover plate; 22. Explosion-proof patch; 23. Explosion-proof valve; 3. Positive electrode current collecting disk; 31. Through hole; 32. Raised portion; 4. Winding core. DETAILED DESCRIPTION

[0026] The present invention will be described in more detail below with reference to the embodiments.

[0027] See also Figures 1 to 4 The positive electrode structure of the cylindrical battery in this embodiment includes an aluminum shell 1 and a winding core 4 sleeved inside the aluminum shell 1. A positive electrode top cover 2 is provided at the positive end of the aluminum shell 1. An explosion-proof valve 23 for discharging gas is installed inside the positive electrode top cover 2, and a positive electrode collecting disk 3 is provided at the inner end of the positive electrode top cover 2.

[0028] Specifically, the inner side of the positive end of the aluminum shell 1 is provided with a first step end face 11, a second step end face 12, a third step end face 13 and a fourth step end face 14, all of which are annular, in sequence from the outside to the inside.

[0029] The inner diameter of the first-step end surface 11 is smaller than the diameter of the winding core 4 , so the winding core 4 can be clamped to prevent the winding core 4 from being ejected when overcharging and thermal runaway occur.

[0030] In this embodiment, the end surface 11 of the first step is in direct contact with the outside world, and the width of the end surface 11 of the first step is 1 mm, which can effectively ensure the stability of the winding core.

[0031] The arc-shaped end surface inside the second-step end surface 12 is welded to the positive electrode top cover 2 and has a width of 0.5 mm, thereby ensuring that the welding line has sufficient weld width and does not affect the step quality.

[0032] In particular, the vertical distance between the second step end surface 12 and the first step end surface 11 is 0.1 mm, thereby preventing the welding line protrusion from affecting the flatness of the first step end surface 11.

[0033] The third step end surface 13 is fitted with the bottom end of the positive electrode top cover 2 to support the positive electrode top cover 2 .

[0034] The fourth-step end face 14 is fixed to the positive electrode current collecting disc 3 by penetration welding, and the thickness of the fourth-step end face 14 is 0.3 mm, which can ensure that there is sufficient air leakage space between the explosion-proof valve 23 and the positive electrode current collecting disc 3, and the instantaneous gas generated after overcharging and thermal runaway can flow to the explosion-proof valve 23.

[0035] Specifically, the positive electrode current collecting disc 3 includes a fixing plate, a through hole 31 is provided at the center of the fixing plate, and five protrusions 32 are evenly provided around the through hole 31 at the top of the fixing plate. The setting of the five protrusions 32 can ensure that the force between the positive electrode current collecting disc 3 and the winding core 4 is stable after it is welded and fixed.

[0036] In this embodiment, one end of each protrusion 32 is connected to the through hole 31, and the other end is arranged near the edge of the fixing plate, and the distance between the free end of the protrusion 32 and the edge of the fixing plate is 1 mm, thereby ensuring that there is no need to identify and locate the position of the protruding welding line during penetration welding, which can improve production efficiency, and the height of the protrusion 32 is 0.1 mm, thereby ensuring that the positive electrode current collecting disk 3 and the winding core 4 are well welded.

[0037] Furthermore, the positive electrode top cover 2 includes a top cover plate 21, which is fixedly connected to the aluminum shell 1 by surface welding, which can increase welding efficiency and yield. A chamfer is provided at the bottom edge of the top cover plate 21 to facilitate the assembly of the top cover plate 21. A mounting hole that cooperates with the explosion-proof valve 23 is provided at the center of the top cover plate 21, and an explosion-proof patch 22 is fitted on the top of the mounting hole.

[0038] In particular, the mounting hole is set at the center of the top cover plate 21, and the gas generated instantaneously during safety tests such as overcharging and thermal runaway can be gathered in the center and discharged smoothly, ensuring the safety of the core 4.

[0039] The working principle of the present invention is as follows: 1. The arrangement of the fourth-step step end face 14 of the aluminum shell 1 and the raised portion 32 of the positive current collecting disc 3 can ensure that there is a sufficient pressure relief channel between the explosion-proof valve 23 and the winding core 4, and the inner diameter of the first-step step end face 11 of the aluminum shell 1 is smaller than the diameter of the winding core 4, which can ensure that the winding core 4 will not be ejected, thereby solving the problem of the safety risk caused by the explosion-proof valve 23 at the positive end of the cylindrical battery being blocked and unable to open the valve in time.

[0040] 2. By setting the mounting hole at the center of the top cover plate 21, that is, setting the explosion-proof valve 23 at the center of the top cover plate 21, the gas generated instantaneously during safety tests such as overcharging and thermal runaway can be gathered at the center and discharged smoothly, ensuring the safety of the core 4.

[0041] In the description of the present invention, it should be noted that the terms "inside", "outside", "upper", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0042] In the description of this utility model, it should be noted that, unless otherwise specified or limited, the term "connection" should be understood in a broad sense. For example, it can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean internal communication between two components. For those skilled in the art, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0043] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

Claims

1. A positive electrode structure for a cylindrical battery, comprising an aluminum shell (1) and a winding core (4) sleeved inside the aluminum shell (1), wherein the positive end of the aluminum shell (1) is provided with a positive electrode top cover (2), an explosion-proof valve (23) for exhausting gas is installed inside the positive electrode top cover (2), and a positive electrode current collecting disk (3) is provided at the inner end of the positive electrode top cover (2), characterized in that: At least three layers of stepped surfaces, all of which are annular, are sequentially provided on the inner side of the positive terminal of the aluminum shell (1) from the outside to the inside, the inner diameter of the outermost stepped surface is smaller than the diameter of the winding core (4), the innermost stepped surface is fixedly mounted on the positive electrode current collecting disk (3), and the penultimate stepped surface is fitted with the positive electrode top cover (2); the positive electrode current collecting disk (3) includes a fixing plate, a through hole (31) is provided at the center of the fixing plate, and at least three protrusions (32) are evenly provided on the top of the fixing plate around the through hole (31).

2. The positive electrode structure of a cylindrical battery according to claim 1, characterized in that: The step surface is provided with four layers, namely a first step end surface (11), a second step end surface (12), a third step end surface (13) and a fourth step end surface (14); the width of the first step end surface (11) is at least 1 mm, the width of the second step end surface (12) is at least 0.5 mm, and the thickness of the fourth step end surface (14) is at least 0.3 mm.

3. The positive electrode structure of a cylindrical battery according to claim 2, characterized in that: The vertical distance between the end surface (12) of the second step and the end surface (11) of the first step is at least 0.1 mm.

4. The positive electrode structure of a cylindrical battery according to claim 1, characterized in that: There are five protrusions (32), and each of the protrusions (32) has one end connected to the through hole (31) and the other end arranged close to the edge of the fixing plate.

5. The positive electrode structure of a cylindrical battery according to claim 4, characterized in that: The distance between the free end of the protrusion (32) and the edge of the fixing plate is at least 1 mm.

6. The positive electrode structure of a cylindrical battery according to claim 1, characterized in that: The height of the protrusion (32) is at least 0.1 mm.

7. The positive electrode structure of a cylindrical battery according to claim 1, characterized in that: The positive electrode top cover (2) comprises a top cover plate (21), a mounting hole matched with an explosion-proof valve (23) is provided at the center of the top cover plate (21), and an explosion-proof patch (22) is fitted on the top of the mounting hole.

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